Thread-controller for sewing machines



March 2, 1948.

E. P. SPAINE THREADCONTROLLER FOR SEWING MACHINES Filed May 18, 1946 7Sheets-Sheet 1 Edwwi'd Spa/inc,

March 2, 1948. E. P-. SPAI'NE THREAD-CONTROLLER FOR SEWING MACHINESFiled may 18, 1946 7 sheets-sheet'z Edward P 15 pain/ March 2, 1948. E.P. SPAINE 2, ,0

v I THREAD-CONTROLLER FOR SEWING MACHINES Filed May 1a, 1946 7Sheets-Sheet 4 ilnv wrw Edward I? Spmine,

March 2, 194 -8.

E. P. SPAINE THREAD-CONTROLLER FOR SEWING MACHINES Filed May 18,.1946

7 Sheets-Sheet 5 DWELLING AT UPPER END OF 5720K:

THREA DEB LOOPE NEEDLE A T LOWE? END OF 5 TPOK E @iward P Spazlne March2, 1948-. E. P. SPAINE' THREAD-CONTROLLER FOR SEWING MACHINES Fi l-edMay 18, 1946 7 Shee'bS She et 6 Edward P Patented Mar. 2, 1948THREAD-CONTROLLER FOR SEWING MACHINES Edward P. Spaine, Bridgeport,Conn, assignor to The Singer Manufacturing Company, Elizabeth, N. J acorporation of New Jersey Application May 18, 1946, Serial No. 670,801

9 Claims.

1 This invention relates to sewing machines and particularly to themeans for manipulating and controlling the under thread of a two-threadsewing machine during the stitch-forming cycle .in order that the underthread will not be subusual purl can be accurately positioned relativelyto the buttonhole slit, second, a better threadluster on the finishedbuttonhole can be assured due to the absence of excessive thread-tensionduring the critical periods of stitch-formation, third, poorer grades ofcotton needle threads can be used because of the fact that the variousloops of one of the sewing threads formed about the other sewing threadduring the concatenation of the threads are not prematurely closed andconsequently do not effect a "choking action on the thread and, fourth,a very heavy looper thread can be employed because of the ready andproper yielding of the accurately controlled and lightly tensionedlooper thread, which heavy looper thread can be used to good advantagein the production of so-called imitation hand buttonholes.

I accomplish this object by providing a threadcontrolling means properlylocated and timed with respect to the movable thread-carrying looper asto differentially modify the action of the looper on the thread to theextent that, during the entire stitch-forming cycle, the looper threadis subjected to a uniform light tension or control essential to thesuccessful high speed operation of a two-thread chain-stitch buttonholesewing machine.

In buttonhole sewing machines of the type herein illustrated, the underor looper thread mechanism is usually supported on a rotary turretsituated beneath the work, the under thread mechanism including anoscillatory thread-carrying looper and complemental loop-retainers whichare actuated by a reciprocatory hollow driving bar. The looper thread,in its passage from its source of supply to the looper, travels throughthe hollow loop-retainer driving bar and then to the heel of thethread-carrying loo-per.

The hollow reciprocatory loop-retainer driving,

bar and the oscillatory looper efiect a varying take-up action orcontrol on the looper thread during each stitch-forming cycle, Thiscontrol 2- is inadequate for successful operation of the stitch-formingdevices.

In the present embodiment of my invention I have shown a preferredconstruction in which an additional thread-controlling element isfastened to the reciprocatory loop-retainer driving bar; saidthread-controlling element being disposed to engage the loo-per threadbetween the threaddelivery end of the loop-retainer driving bar and theheel of the oscillatory looper. The position of the additionalthread-controlling element relative to the loop-retainer driving bar andthe heel of the looper is such as to combine its takeup action with thatof the loop-retainer driving bar and the looper additively during aportion of a, stitch-forming cycle and subtractively during anotherportion of the cycle. As a net result, the three movable elements insurethe desired yielding of the looper thread at the required times and thedesired take-up action on the thread in compl ting a stitch at the righttimes, without leaving any uncontrolled slack in the thread at any time.

For the practical operation of a two-thread sewing machine, it isnecessary also that an accurate control of the needle-thread beexercised. To that end, the machine illustrated is equipped with acam-actuated take-up constructed substantially in accordance with thedisclosure in my.U. S. Patent No. 2,165,016, dated July 4, 1939,

In order to give a complete understanding of the present invention Ihave illustrated in the drawings a selected embodiment thereof whichwill now be described after which the novel features will be pointed outin the appended claims.

Fig. 1 'is a right side elevational view of a buttonhole machineembodying the invention.

Fig. 2 is an elevational view of the looper thread stitch-by-stitchpull-01f mechanism employed for drawing from the looper thread supply alength of thread sufl'icient to complete each stitch, the thread armbeing shown in full lines in its maximum pull-oil position and in dottedlines in its retracted position.

Fig. 3 is a front end elevational view of the machine shown partly insection.

Fig, 4 is a longitudinal vertical sectional view of the looper threadmechanism, showing the details of the actuating connections therefor.

Fig. 5 is an enlarged horizontal sectional view taken substantiallyalong the line 55, Fig. 4.

Fig. 6 is a top plan view of the needle thread take-up device, with thetop cover plate broken away to more clearly show the development of theactuating cam.

Fi 7 is a fragmentary View of a portion of a buttonhole, illustratingthe way in which the purl-concatenations are uniformly and. tightly setclose to the buttonhole slit.

Fig. 8 is a View, partly in section, of the stitchforming mechanism,showing several stitches completely formed in a fragment of work held inthe work-clamp and the components of the stitch-forming mechanism andthe sewing threads in position to begin the formation of the nextstitch.

Fig. 9 is a front elevation of the turret with the work-clamp andneedle-throat member in section, showing the stitch-forming mechanismcomponents and sewing threads in position at the commencement of astitch-forming cycle.

Fig. 10 is a right side elevation of the turret with the needle-throatmember in section, showing the first step in the stitch-forming cycle inwhich the needle has descended to begin the slitstitch and entered thespread loop of needle thread detained by the right hand loop-retainer.

Fig. 11 illustrates the stitch-forming devices in their next position ofstitch-formation, the detained needle-thread-loop having been releasedby the right hand loop-retainer and the threadcarrying looper havingadvanced and entered the next needle-thread-loop cast out by theascending needle.

Fig. 12 is a front elevation, partly in section, of the parts shown inFig. 11.

Fig. 13 shows the next position of stitch-formation in which thethread-carrying looper has traveled to the end of itsneedle-thread-loopseizing stroke and in so doing has positioned a limbof its own thread for seizure by the advancing left hand loop-retainer.

Fig. 14 is a front elevation, partly in section, of the parts shown inFig. 13.

Fig. 15 shows the position of the stitch-forming devices atsubstantially the completion of the slit-stitch, in which position thelooper-threadloop is detained on the left hand loop-retainer.

Fig. 16 is a front elevation, partly in section, of the parts shown inFig. 15.

Fig. 17 shows the next position of stitch-formation in which the needlehas penetrated the work to form the depth-stitch and has entered thelooper-thread-loop held spread by the left hand loop-retainer.

Fig. 18 is a front elevation, partly in section, of the parts shown inFig. 17.

Fig. 19 shows the needle at the bottom of its depth-stitch stroke, thelooper-thread-loop having been released by the left hand loop-retainerand the loop being taken up by the retracting thread-carrying looper andmy improved threadcontroller.

Fig. 20 is a front elevation, partly in section, of the parts shown inFig. 19.

Fig. 21 illustrates the parts in the position after the non-threadedlooper has seized the needlethread-loop cast out by the needle andPresented said seized loop for engagement by the advancing right handloop-retainer.

Fig. 22 is a front elevation, partly in section, of the parts shown inFig. 21.

Fig. 23 is a rear elevational View of the turret, showing the details ofthe looper oscillating connections.

Fig. 24 is a left side elevational view of the turret.

Fig. 25 is a top plan view of the turret; with the shank of theneedle-throat-member in section and the remainder of theneedle-throat-member shown in dotted lines.

Fig. 26 is a development showing the action of the needle, needle-threadtake-up, thread-carrying looper and my thread controller on the twosewing threads during the complete stitch-forming cycle covering 720degrees rotation of the arm-shaft of the sewing machine.

Referring in detail to the accompanying drawings, the invention is shownas embodied in a machine of the buttonhole type having, in general,constructive features which are substantially in accordance with thedisclosure of the U. S. patent to Allen, No. 15,324, reissued April 4,1922. The machine-frame is formed with a hollow box-like bed 3%) fromthe rear end of which rises a standard 31 of an overhanging bracketarm32 terminating in a head 33. Supported on the bed 32 is the usualtraveling work-holder comprising the lower work-supporting plates 34 andthe upper clamping members 35, to which workholder longitudinal feedingand sidewise shifting movements are imparted for spacing the stitches ofa buttonhole. The work-holder is moved relative to the stitch-formingmechanism during the sewing period as well as prior and subsequent tothe sewing period by the usual connections with the feed-wheel 3%, asdisclosed in said Allen reissued Patent No. 15,324.

The stitch-forming mechanism is constructed substantially in accordancewith the disclosure of the Allen et al. Patent No. 1,372,473, dated Mar.22, 1921. It is driven by means including a main sewing shaft 31, Fig.1, journaled within and lengthwise of the bed 39, which main shaft 37,through one-to-one bevel gears 38, 3!), drives a vertical shaft Mljournaled within the standard 3!. The shaft 4t has a one-to-twospeed-multiplying bevel-gear driving connection 4|, 42 with an upper orneedle-bar-reciprocating shaft 43 which is journaled within and extendslengthwise of the bracket-arm 32 and has the usual crank M andlink-connection 45 with a vertically reciprocatory hollow needle-bar 55mounted in the head 33.

The hollow needle-bar 46, Figs. 1 and 3, has fixed to its lower end ayoke 31 carrying a crosspin id on which is slidably mounted aneedleclamp-block 49 and embracing at its upper end the horizontalportion of the yoke 47. The block 49 carries an eye-pointed threadcarrying needle 50. During its reciprocation, the yoke 41 is steadied bya vertical guide-member 55 depending from the lower end of a needle-barbearing bushing 52 journaled in the head 33 and having a pinion 53 fixedto its upper end, whereby turning movements may be imparted to it, as institching around the eyelet-end of a buttonhole. As fully explained inthe Allen et al. Patent No. 1,372,473, the needl-clamp-block 49 isadapted to be laterally vibrated on the cross-pin 49 through suitableconnections with an internally grooved ringmember 5-? fixed to the lowerend of a vertical slide-rod 55, Fig. 1, journaled in the head 33. Theslide-rod 55 is reciprocated by means of. a link 55 adjustably andpivotally secured to the slotted limb of a bell-crank lever 51 fulcrumedat 53 on the head 33. The other limb of the bellcrank lever 51 isconnected by a. link 58 to an arm 5%! fulcrumed at its rear end on thebracketarm 32 and actuated by an eccentric fast on the vertical shaft40, in a manner fully disclosed in the above mentioned Allen et al.Patent No. 1,372,473.

Cooperating with the endwise reciprocatory and laterally shiftableneedle 50, in the formation of stitches, are under thread-handlingimplements supported in the usual manner on a rotary turret Blhavinga.tubular shank 62 journaled in a vertical bearing aperture 63, Fig. 4,in a frameblock 64 detachably secured to the machine-bed 30. Extendingupwardly from the turret 6| is a post 65 into the upper extremity ofwhich is threaded a horizontal pivot-screw66 on which is fulcrumed alooper-carrier 61 formed with oppositely extending arms to which arerigidly secured the threaded and non-threaded loopers 56 and 69. Thethreaded looper .68 is provided adjacent its point or beak with athread-eye I6 and in its heel with a pair of thread-eyes II and 12. Thenon-threaded looper 69 is formed with a loop-seizing beak 13 at theopposite sides of the base of which are formed loop-arresting shouldersT4.

The actuating connections for the loopers 68 and 59 comprise a link Isecured at its upper end to one arm of the looper-carrier 61, Figs. 23and 24, and at its lower end to the offset head '16 formed on the upperend of a tubular rod If, Fig. 4, fitted to slide within the tubularshank 52 of the turret 6i. At its lower end the tubular rod TI is formedwith a circumferential groove 78 which is entered by the forkedextremity of an arm I9, Fig. 3, clamped on a guide-rod 85 journaled toslide vertically in bearing lugs provided on the frame-block 64. The armI9 is thus adapted to lift and lower the tubular rod 1'! and therebyrock the looper-carrier 61 about its fulcrum-stud 65. The means forraising and lowering the arm 19 preferably includes a link 8|,

Figs. 3 and 4, connected at its lower end to a crank 82 carried on theforward end of a short shaft 83 journaled in the frame-block 64. At

its inner end, the shaft 83 carries a pinion84 meshing with a gear 85 oftriple its size supported by a stud 86 carried by the frame-block 64.Secured to the rear face of the gear 85 is a starwheel 87 which hasimparted to it step-by-step turning movements by means of a pair ofdriving pins 83 arranged diametrically of a driving disk 59 secured tothe main sewing shaft 31. As fully explained in the above mentioned '0.S. Patent No. 1,372,473, the teeth of the star-wheel 81 are shaped suchwise as to produce periods of appreciable dwell between the periods ofmotion of the star-wheel. During these periods of dwell the crank 82 isheld stationary at one or the other of its positions midway between itsextreme up and down positions, thus arresting the motion of the loopersmidway between the extremes of their strokes to avoid interference withthe loopretainers now to be described.

Cooperating with the threaded looper 68 is a loop-retainer 90hereinafter referred to as the right hand loop-retainer. As showninFigs. 4, 10, 23 and 25, the right hand loop-retainer 90 is mounted on acarrier-lever 9I fulcrumed to oscillate about a horizontal pin 92supported at its opposite ends by the spaced vertical posts 93 extendingupwardly from the turret BI. At its free end the right handloop-retainer 90 is formed with a curved and pointed loop-seizing horn94 which, as will be explained later, functions to enter and retaincontrol of a needle-thread-loop presented to the loop-retainer by thenonthreaded looper 69. overlying the horn 94 is a curved pilot 9 3 whichfunctions to deflect the looper thread above the horn 94 when theloopretainer 90 is advancing to enter the needlefulcrumed on thehorizontal pin 92. Like the first loop-retainer 90, the secondloop-retainer 95 is formed at its free end with a curved and pointedloop-seizing horn 91. The two 10op-re tainers 90 and 95 are oscillatedon their common fulcrum-pin 92 by means including two links 90' and 99,Fig. 4, connected at their upper ends to the carrier-levers 9| and 96and at their lower ends to the opposite ends of a cross-head I00.

The cross-head I00 is preferably integral with the upper end of a rodIOI bored longitudinally to provide a looper-thread passagewa I02. Therod IN is slidingly fitted within the tubular rod TI and has clamped toits lower end two collars I03 and I04 spaced to provide acircumferential groove I05 adapted to receive the forked extremity of anactuator arm I06 projecting forwardly from a slide-plate I 01 fitted toa slideway I90 in th transverse bed-partition I09. The slideplate iscaused to reciprocate in the slideway I06 by a roller IIO carried by theslide-plate and tracking a suitable cam-groove III cut in the rear faceof the driving disk 89. Through the connections just described it willbe understood that rotation of the main sewing shaft 31 causes thedriving disk 89, through the star-wheel 81, to impart to the threadedand non-threaded loopers 68 and 69 a variable motion and at the sametime, through the cam-groove I I I, to actuate the right and left handloop-retainers and in proper sequence to effect stitch-formation;

To properly support the work W at the stitching point, there is providedthe usual needlethroat-meinber or button I I2 apertured at its upperfree end, as at II3, to provide needle-clearance, and adjustablysupported at its lower end on a, vertical post II4 integral with theturret GI. The needle-throat-member II2, when correctly mounted, liesdirectly above and very close to the path of movement of theretainer-horns 94 and 91 which, it will be seen, operate at an elevationbetween the loopers 68 and 69 and the throat-member II2.

The mechanism for turning the stitch-forming mechanism in stitchingaround the eyelet-end of a buttonhole is constructed substantially inaccordance with the disclosure in the E. E. Allen Patent No. 1,162,207,Nov. 30, 1915. Suffice it to say that the needle-bar mechanism carries agear 53,-Figs. 1 and 4, and the turret carries a similar gear II5, thesegears having in mesh therewith tWdgear-segments H6 and II! connectedtogether by mechanism deriving its actuation from the feed-wheel 36. 4

To control the needle thread N the present machine has mounted on top ofthe bracket-arm 32 a common form of thread take-up mechanism disclosed,for instance, in my U. S. Patent No. 2,165,016, July 4, 1939. Thetake-up mechanism includes a housing IIB, Figs. 1 and 6, enclosing atake-up cam II9 which is mounted on a shaft I20 gear-driven by theneedle-bar reciprocating shaft 43. Pivotally mounted at I2I, Fig. 6, inthe housing I I8 is a take-up lever I22 carrying intermediate its ends afollower roll I23 which enters the take-up cam-groove I24. The take-uplever I22 has at its free end a thread-eye I25 which acts upon theneedle thread N between a conventional tension device I26 and the hollowneedle-bar 46 through which the needle thread runs to the needle 50. Asshown in Figs. 1 and 6, the needle thread N travels from a source of 7.supply through aguide hole (not shown)" in: a post I21, thence betweenthe disks oi the tension device i253, thence up throughafixed threadeyeHe in one limb of a-u -shaped plata 1 2a fast on the housing cover-plateI-30 andthen down through a fixed thread-eye lz'il in the other limb ofthe-plate F29 and throughthetake up thread eye I253 thence forwardly"through the open thread-nipper E32 and down through the hollowneedle-bar 46 into the thread-retainer I33, Fig. 3,- and then to theneedle 59. It will be appreelated that for perfectstitch-formation anaccurate control of the needle thread must be maintained and that thecontrol exercised must bear a definite relation: to that applied to thelooper thread. Sucha control of n'eedle'thread is accomplished with theaid of the: take-up camgroove 24 which is preferably cut to operatethetake-up lever 522 so that its. thread require-- ments areas indicated inFig; 26.

The course: of travelv of the looper thread L is best shown inFigs. l,2rand S. From-asupply the looper. thread passes through' a guide-tube I31, thence through-a thread-eye I35 providedin the free end-portion ofathread pull off lever I36 frictionally fulcrume'd at I31 on the bed 30:The thread pull-off lever I36. is: oscillated about its fulcrum I31 fromthe dotted lineposition to the full line position, Fig 2, by thealternate-em gagement of-the spacedarmsltd and I-39'by the two pins useand Hi! carried on adisk I42-fast on a cross-shaft I43, in a manner:fully shown in U. S. Patent No. 2,210,638, Aug. 6; 1940. 'One completestroke is imparted tothe threadipulbofi lever I 36 during the complete.buttonholing. cycle, thelength of slack looper thread thus providedbeing suflicient to complete thestitching cycle.

From the thread-eye I35; the looper thread runsthrough a guide-hole Hi4,Figs. 2 an'd3,-in the bed 38, thencethrough a self-threading wirethread-guide M5 to and through the regular tension device I58, andthenup' through the bore I02 of the loop-retainer actuating rod H. Inprior machines it has been customary: to lead the looper thread Ldirectly from theupper end of the hollow rod H to and throughthethreadeyes in the threaded looper 68.- The threadcontrollingaction-obtained by the reciprocatory loop-retainer driving bar mland theoscillatory looper 68 only approximated that required and,

to resilient check-springs and other similar devices had to be employed.Thesedevices improved the thread-handling to some extent; but were notentirely satisfactory. V

The present invention contemplates the use of a thread-controller,indicated generally as-G, disposed to operate on the looper thread-asitpasses from the upper end of the loop-retainer driving bar IM to theheel of the thread-carryinglooper- E8. The improved thread-controller isadapted to be carried by the loop-retainer driving; bar IM and thereforepartakes of the vertical reciprocation thereof. The resultant movementof-the controller working in conjunction with the oscil 7 latorythread-carrying looper 63' and withother of the movable elements of theunder thread handling mechanism forms a bight in the looperthread whichvaries in size. The effect of this varying nightis a control of thelooper thread L such that the thread is devoid of excessiverier-leverlink 99 to the cross-head I00, .is fornied satisfactorilyhandle the looper thread,-

8 with an: extension M1 on which is adi-ustably clamped by means ofascrew I48 the lower end of the shank I 49 or my" improvedlooper-threadcontroller. Attheupper end, the shank I49 terminates in anonset head I50 formedwitn a vertically disposed aperture I5I, Fig. 13-,intersected by aslot I52 cut in the top face of the oifse't' headI'5El,.the aperture and slot providing a thread-eye through which thelooper thread travels. To facilitate threading the aperture I5I,

illustrated form of thread-controller mounting also provides forallowing a small degree ofoilcular adjustment ofthe controller-elementabout the axis of the extension I41.

To aid-indescribing a cycle of operations of the stitch-formingmechanism,- attention is directed to Figs. 8 through-22,- inclusive.Letit be understood thatin the present case: a complete stitch-formingcycle includes two complete reciprocations of the needle, the cyclebeginning with the needle in raised position preparatory todescendingtoformthe so-called slit-stitch. Since two reciprocations ofthe needle are included-in the complete stitch-forming cycle,thearm-shaft t3 rotates through 720' degrees. With this in l mind;assume now that the machine has produced several stitches and that theparts are in the positionshown inFigs;- 8 and 9, with a 1001) I56 ofneedle thread detained and held' spread on the horn 94 of the right handloop-retainer 9i), and

=with the thread-carrying looper 68 in a position of dwell awaiting thedescent of the needle 52 to begin the slit-stitch. Withthe parts inthese positions, the'thread-controllerC isalso in a state of dwell-sinceit is mounted on'the loop-retainer driving rod- Iill which, asmentionedab-ove, is stationary at this time. Continuing withthe cycle;the needle 56 now descends through the work W and entersthe=needle-thr'ead-loop I5=l detained by the horn it of the righthand-locoretainer 1% (Fig. 10). During the descent of the needle fibtowardthe work -W, the needle threadtake-up lever I22 isa-ctuated'in adirection to absorb the slack in the needle 'threa'd'i'iroduced by. thedescending needle-bar. when the needlepoint-penetrates the work, theneedle thread take needle-thread-loop I541 about the needle 53, as showninFig; l1. Then-eedle 5i! then-travels-to thehottom :01" its stroke,after-which it begins to ascend, l casting out the needle-thread-loopI55 which isenteredby the advancing thread-carry- !56', Fig. 10, therighthand-retainer til-is retracted, leaving the 9 ing looper 68, asshown in Figs. 11 and 12. As the looper 68 passes the needle 59 in itsloopseizing stroke, the needle thread take-up lever I22 is operated totake up a slight amount of thread to partially close the cast-outneedlethread-loop I55, thereby preventing said loop I55 from twisting ina direction away from the beak of the looper 68 and also to provide apurchase on the needle-thread enabling the needle-bar better to work indrawing up the preceding needlethread-loop I54 to the inside edge of thepurl formation. After the looper 68 enters the cast outneedle-thread-loop I55, the needle 55 is withdrawn from the work and thelooper 53 continues in its advance until it reaches the end of itsloopseizing stroke, Figs. 13 and 14.

During the movement of the parts from the positions shown in Fig. 11 tothe positions shown in Fig. 14, the thread-controller C moves upwardlyto assist in giving some slack looper thread to the advancingthread-carrying 1ooper 68. But, near the end of theadvancing stroke ofthe looper 68, a sufficient bight is formed in the looper thread (Fig.14) to effect a control action on the looper thread. This control actionresults in a straightening of the limb I56 of looper thread extendingfrom the thread-eye I in the looper 53 to the previous stitch in thework (Fig. 14), thus positioning the limb I55 across the path ofmovement of the loop-retainer 95 so that the horn 91 of theloop-retainer unerringly seizes said'thread-limb I55. After seizure ofthe looper-thread-limb I55 by the left hand loop-retainer 95 (Figs. 13and 14), the continued upward movement of the threadcontroller C and thebodily upward movement of the loop-retainer driving bar I flI provideslack looper thread for the formation of the looperthread-loop I! (Figs.15 and 16) which is detained by the horn 91 of the left handloop-retainer 95 after the thread-carrying'looper 98 has retracted farenough to release the needle-threadloop I55. Continued retraction of thethreadcarrying looper 69 provides additional slack looper thread, whichslack thread is augmented slightly by the continued upward movement ofthe thread-controller C so that sufficient tension-free looper thread isfurnished to permit the needlethread-loop I55, cast off by the looper68, to be pulled up in response to the needle thread takeup action, tothe purl-forming position at the under side of the work, as shown inFig. 16. As the needle-thread-loop I55 is pulled up to its purl-formingposition, it carries with it the looper thread forming the thread-loopI5! (Fig. 16). The amount of looper thread made available by thethread-controller and the thread-carrying looper 59 is sufiicient sothat when the needlethrea-d loop I55 is pulled up to purl-formingposition, the looper-thread-loop I51 on the horn 9'! of the left handloop-retainer 95 is caused to slide up the horn into the throat thereof'(Fig. 15) thus opening or spreading the looper-thread-loop I5! forpositive entrance by thedescending needle 55 on its nextwork-penetrating stroke, as shown in Figs. 17 and 18. It is desirablethat the looper thread be properly controlled at this critical time vinthe cycle, for if the looper thread is undercontrolled and there is toomuch slack looper thread the thread-loop I5! on the loop-retainer horn91' will not be drawn up into the throat of the horn. Consequently, thethread-loop I51 will not be spread suiiiciently to insure the unerringentrance thereof by the needle. Further, if the looper thread isover-controlled at this time, the thread will be excessively tensionedand therefore the thread-loop I51 will not cast free of theloop-retainer horn 91 at the correct instant, but will hang on the horncausing either a stealing of looper thread from the supply or a pullingdown of the previous needle-thread-loop I55 from its purl-formingposition. This pulled down or displaced needle-thread-loop I55 must bereset. This resetting however cannot always be accomplished andparticularly when the pull on the thread, resulting in the displacementof the previous needle-thread-loop I55, has closed or tightened any ofthe previous unset thread-loops. Later in the stitch forming cycle, thefailure in resetting the needle-thread-loop I55 into its normalpurl-forming position up against the under side of the work (Figs. 21and 22) will result in lowering the lead of that portion of the looperthread L extending from the needle-thread-loop I55 to thelooper-thread-eye 10, to a position below the level of the point of thepilot 94' on the advancing right hand loop-retainer 99. Should thisoccur, the looper thread will be engaged by the advancing loop-retainer99 and pushed to an abnormal position, i. e. from one side to the otherside of the needle 59. This causes an abnormal concatenation of thesewing threads and results in a malformed or rough purl.

When the needle-thread-loop I55 has been properly pulled up topurl-forming position and the looper-thread-loop I5'I is-detained on thehorn 91' of the left hand loop-retainer 95 (Fig. 16) thethread-controller C is positioned at the top of its stroke. The needle59 now descends to start the depth or bight stitch, penetrating the workW and entering the looper-thread-loop I51, as shown in Figs. 17 and 18.After the needle 59 has entered the looper-thread-loop I51, the lefthand'loop-retainer 95 is retracted, causing the horn 97 thereof to shedthe loop I51 on the needle 50. The needle then continues to the bottomof its stroke and begins its ascent to cast out a needle-thread-loop I58. The nonthreaded looper 69 now advances in the direction indicated bythe arrow in Fig. 20, to seize the needle-thread-loop I58 cast out bythe needle. After seizure of the thread-loop I58 by the beak 13 of thenon-threaded looper 59, the needle 59 is withdrawn from the work W andthe nonthreaded looper 69 carries the needle-threadloop I58 to the rightas shown in Fig. 22, thereby to position it for entrance by the horn 94of the right hand loop-retainer 99. During the movement of the partsfrom the position shown in Fig. 18 to the position shown in Fig. 22, thelooper-thread-controller C moves downwardly and augments the take-upaction of the threaded looper 58 and the loop-retainer driving bar IIlIto the extent of, first, properly reducing the looper-thread-loop I5!about the needle and,

second, of taking up the slack looper thread created by the retractionof the threaded-looper 58, whereby the lead of the looper-thread extending from the needle-thread-loop I55 to the looper-thread-eye III(Fig. 22) will be above the advancing point of the pilot 94 on theloopretainer 95. By maintaining the lead of the looper thread above thepoint of the advancing pilot'94, the looper thread will be directed overthe top of the loop-retainer during each stitchforming cycle, thusinsuring a uniform positioning of the looper thread to the left of theneedle as viewed in Fig. 10. This constant relative disposition oflooper thread with respect to the needle insures a uniform concatenationof the threads forming the purl.

After the; right hand loop-retainer 963,- has entered andv seized: theneedle-thread-loop tad presentedv by the non-threaded looper 69,, thelatter is-lretractedi from its advanced position. shown in Fig; 22-: to;an, intermediate; dwell position: shown in Fig; 9. Thev thread-carryinglooper; 68 has advanced to its: intermediate dwell, position inreadiness for, the descent of. the, needle to start the nextslit-stitch; The complete stitche-iorming'cycle, has. now beenperformed.

While Ihave not. described in detail the action the. needle; thread ofthe take-up lever I22, it will be: understood that accurate control ofthe; needle. thread is. essential. This control is illustrated: in Fig.25,.whi'ch discloses a diagram or: dvelopment ofthe displacement of the.needle fillpandg looper 63, the, thread-control of the needle threadtakeeup. andthe control produced by the thread-controller C; Thepositions lengthwise of the diagram indicated by the verticallydisposedarrows and numerals 8 to 22', inclusive, correspondrespectively, with the periods of the stltcheformin'g cycle shown inFigs. 3 to 22, inelusive;

From the above. description, it will be evident that the exactingthread-control made possible by my improved controller renders themachine capable of producing buttonholes of highest quality; One of'thefactors contributing to this is'the uniform formation of the purl closeto and paralleling the slit of the buttonhole. While a uniform formationand location of the purl has beenheretoforeattained in buttonholemachines, this was: accomplished by using hard finished cords ot'goodsize in combination with a strong tension, causing the purl to rolltoward the slit. This method proved successful on material of a firmweave, but not so successful on material of a flimsy nature, such ascottons having a basket or diagonalweave. The present improvement has:adapted the machine for sewing equally well onfirm or flimsy weavematerials. It is further desirablethatthe maximum degree of lustrebepreserved on. the sewing threads in the finished button-hole. It is wellknown that the thread lustre is reduced when the thread is excessivelytensioned In prior machines the thread-control was at best anapproximation and as a result thereof'the loops of thread duringstitch-forms. tion were unavoidably prematurely closed. This choking ofthe thread-loops had to be overcome lay-excessively tensioning thethreads, causing not only a reduction in the lustre of the completedbuttonhole but minimizing the ability of the machine tohandlesuccessfully the poorer I. A two-thread sewing machine having work- Hholding means" and stitch-forming mechanism which are relatively movableto space stitches, saidstitch -formingmechanism including an endwisevreciprocatory and laterally'vibratory threadcarrying needle, a threadedlooper and a non- 1'2 threaded looper adapted: alternatelyto entthread-loops presented by said needle, loop-retainers, for seizing:thread-loops from; said loopers and presenting themior entrancegby'saidneedle, means for. actuating saidl stitch-forming mechanism. including adriving bar operatively connected to said. loop-retainers,thread-guiding means carried, by said driving bar for directin thread tosaid threadedlooper, and a threadcontroller adapted to engage. thethread between said thread-guiding means and? said threaded looper,

2. A two-thread sewing machinehaving workholding means and,stitch-forming mechanism which are relatively-movableto spacevstitches,said stitch-forming mechanismv including an. endwisc reciprocatory andlaterally'vibratory thIGHJdrCEY- rying needle, a threaded. looperand anonthreaded looper adapted alternately to enter thread-loopspresented bysaid'needle, loop-retainers for seizing thread-loops; from. said.loopers and presenting them. forxentrance by said: needle, means: foractuating said stitch-forming mechanism including a. reciprocatorydriving bar operatively connected-.to-saidloop-retainers, threadguidingmeans carried bysaid drivingabar for'directing thread to said threadedlooper, and a thread controller movable in a right line parallel to-theaxis of said driving bar and disposed toengage; the thread between, saidthread-guiding means and said threaded-looper.

3. A two thread sewing machine having workholding means andstitch-forming mechanism which are relativelymovableto, space stitches,said stitch-fo'rming mechanism including an endwise reciprocatory andlaterallyvibratorythreadcarrying needle, a threaded looper and anonthreaded looper adapted alternately to enter threaddoops. presentedby said needle, loop-retainers for seizing thread-loops from saidloopers and presenting them for: entrance b said needle, means foractuating said stitch-forming mechanism including a. driving baroperatively connected to said loop-retainers, thread-guiding meanscarried. by said driving bar for directing thread to said threadedlooper, and a threadcontroller mounted on said driving. bar and adaptedto engage the; thread between said threa'd' guiding means and saidthreaded looper.

4. A two-thread sewing machine having workholding' means andstitch-forming mechanism which are relatively movable to space stitches,said stitch-forming mechanism including. an endwise reciprocatoryandlaterally vibratory threadcarrying needle, a. threaded looper and anonthreaded loloper' adapted: alternately to enter thread-loopspresented by said needle, loop-retainers for seizingthreadeloopsfrom-said loopers and presenting them for entranceb said needle, meansfor actuating-said stitch-forming mechanism including an endwisereciprocatory driving bar operativelyconnected to. said: loop-retainersand having a looper, thread-guiding boreterminating at the end ofsaidbar adjacenttsaid loop-retainers, and. a thread-controller'mountedon said driving bar and adaptedto engage the threadbatween saidtin'ead-guidingbore andsaid threaded looper;

5. A two-thread sewing machine having workholding means andstitch-forming mechanism which are relatively movable to space stitches,said stitch forming mechanism including an endwi'se reciprocatory andlaterally vibratory threadcarrying needle, means. for varyingtheamplitude of vibration of said needle, threaded? nonthreaded loopersadapted alternatel to enter thread-loops presented by said needle,loop-retainers for seizing thread-loops from said loopers and presentingthem for entrance by said needle, means for actuating saidstitch-forming mechanism including a driving bar operatively connectedto said loop-retainers, thread-guiding means carried by said driving barfor directing thread to said threaded looper, a thread-controlleradapted to engage the thread between said thread-guiding mean and saidthreaded looper, and. means supporting said thread-contrller for varyingthe operative location thereof in accordance with the selected amplitudeof vibration of said needle.

6. A two-thread sewing machine having workholding means andstitch-forming mechanism which are relatively movable to space stitches,said stitch forming mechanism including an endwise reciprocatory andlaterally vibratory threadcarrying needle, mean for varying theamplitude of Vibration of said needle, threaded and nonthreaded loopersadapted alternately to enter thread-loops presented by said needle,loop-retainers for seizing thread-loops from said loopers and presentingthem for entrance by said needle, means for actuating saidstitch-forming mechanism including a driving bar operatively connectedto said loop-retainers, thread-guiding means carried by said driving barfor directing thread to said threaded looper, a thread-controlleradapted to engage the thread between said thread-guiding means and saidthreaded looper, and means supporting said thread-controller andpermitting adjustment of the operative location thereof in a directionparallel to the plane of viv mechanism including a member having avariable reciprocatory motion operatively connected to saidloop-retainers, thread-guiding means carried by said member fordirecting thread to said threaded looper, and a thread-controlleradapted to act on the thread between said guiding means and saidthreaded looper and movable in a path parallel to the line ofreciprocation of and in synchronism with said member.

8. A two-thread sewing machine having workholding means andstitch-forming mechanism which are relatively movable to space stitches,said stitch-forming mechanism including an endwise reciprocatory andlaterally vibratory threadcarrying needle, oscillatory threaded andnonthreaded loopers adapted alternately to enter thread-loops presentedby said needle, loop-retainers for seizing thread-loops from saidloopers and presenting them for entrance by said needle, means foractuating said stitch-forming mechanism including a reciprocatorydriving bar operatively connected at one end to said loop-retainers andhaving a thread-guiding bore extending from one end to the other fordirecting thread to said threaded looper, and a threadcontroller securedto said driving bar and having a thread-engaging free end disposed toact on the thread between the mouth of said threadguiding bore and saidthreaded looper.

9. A sewing machine having, in combination, an endwise reciprocatory andlaterally jogging thread-acrrying needle, oscillatory threaded andnon-threaded loopers cooperating with said needle in enteringthread-loops presented by said needle, a plurality of loop-detainers forseizing thread-loops from said loopers, means for actuating saidloop-detainers including a driving member operable in a right line,thread-guiding means carried by said driving member for directing threadto said threaded looper, and a threadcontroller operable in a right lineand disposed to act on the looper thread between said threadguidingmeans and said oscillatory threaded looper, said thread-guidin means,oscillatory threaded looper and thread-controller summarily effecting adifferential control on the looper thread such that the latter is devoidof excessive strains during the entire stitch-forming cycle.

EDWARD P. SPAINE.

